// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package com.intellij.lang.parser;

import com.intellij.codeInsight.completion.impl.CamelHumpMatcher;
import com.intellij.lang.*;
import com.intellij.lang.impl.PsiBuilderAdapter;
import com.intellij.lang.impl.PsiBuilderImpl;
import com.intellij.lexer.Lexer;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.util.Comparing;
import com.intellij.openapi.util.Key;
import com.intellij.openapi.util.Pair;
import com.intellij.openapi.util.text.StringHash;
import com.intellij.psi.PsiFile;
import com.intellij.psi.PsiReference;
import com.intellij.psi.TokenType;
import com.intellij.psi.impl.source.resolve.FileContextUtil;
import com.intellij.psi.impl.source.tree.CompositePsiElement;
import com.intellij.psi.tree.ICompositeElementType;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.tree.TokenSet;
import com.intellij.util.Function;
import com.intellij.util.PairProcessor;
import com.intellij.util.containers.ContainerUtil;
import com.intellij.util.containers.LimitedPool;
import gnu.trove.THashSet;
import org.jetbrains.annotations.Contract;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.*;

import static com.intellij.openapi.util.text.StringUtil.*;

/**
 * This class is a runtime engine for parsers generated by <a href="https://github.com/JetBrains/Grammar-Kit">Grammar-Kit</a>.
 * <br/>
 * Here is the original <a href="https://github.com/JetBrains/Grammar-Kit/blob/master/support/org/intellij/grammar/parser/GeneratedParserUtilBase.java">
 *   GeneratedParserUtilBase</a> code.
 * <br/>
 * <br/>
 * CAUTION: Authorized personnel only. Do not modify or refactor.
 *
 * @author gregsh
 */
public class GeneratedParserUtilBase {
  private static final Logger LOG = Logger.getInstance(GeneratedParserUtilBase.class);

  private static final int MAX_RECURSION_LEVEL = parseInt(System.getProperty("grammar.kit.gpub.max.level"), 1000);
  private static final int MAX_VARIANTS_SIZE = 10000;
  private static final int MAX_VARIANTS_TO_DISPLAY = 50;
  private static final int MAX_ERROR_TOKEN_TEXT = 20;

  private static final int INITIAL_VARIANTS_SIZE = 1000;
  private static final int VARIANTS_POOL_SIZE = 10000;
  private static final int FRAMES_POOL_SIZE = 500;

  public static final IElementType DUMMY_BLOCK = new DummyBlockElementType();

  public interface Parser {
    boolean parse(PsiBuilder builder, int level);
  }

  public static final Parser TOKEN_ADVANCER = (builder, level) -> {
    if (builder.eof()) return false;
    builder.advanceLexer();
    return true;
  };

  public static final Parser TRUE_CONDITION = (builder, level) -> true;

  public interface Hook<T> {

    @Contract("_,null,_->null")
    PsiBuilder.Marker run(PsiBuilder builder, PsiBuilder.Marker marker, T param);

  }

  public static final Hook<WhitespacesAndCommentsBinder> LEFT_BINDER =
    (builder, marker, param) -> {
      if (marker != null) marker.setCustomEdgeTokenBinders(param, null);
      return marker;
    };

  public static final Hook<WhitespacesAndCommentsBinder> RIGHT_BINDER =
    (builder, marker, param) -> {
      if (marker != null) marker.setCustomEdgeTokenBinders(null, param);
      return marker;
    };

  public static final Hook<WhitespacesAndCommentsBinder[]> WS_BINDERS =
    (builder, marker, param) -> {
      if (marker != null) marker.setCustomEdgeTokenBinders(param[0], param[1]);
      return marker;
    };

  public static final Hook<String> LOG_HOOK = (builder, marker, param) -> {
    PsiBuilderImpl.ProductionMarker m = (PsiBuilderImpl.ProductionMarker)marker;
    int start = m == null ? builder.getCurrentOffset() : m.getStartOffset();
    int end = m == null ? start : m.getEndOffset();
    String prefix = "[" + start + ", " + end + "]" + (m == null ? "" : " " + m.getTokenType());
    builder.mark().error(prefix + ": " + param);
    return marker;
  };


  public static boolean eof(PsiBuilder builder, int level) {
    return builder.eof();
  }

  public static int current_position_(PsiBuilder builder) {
    return builder.rawTokenIndex();
  }

  public static boolean recursion_guard_(PsiBuilder builder, int level, String funcName) {
    if (level > MAX_RECURSION_LEVEL) {
      builder.mark().error("Maximum recursion level (" + MAX_RECURSION_LEVEL + ") reached in '" + funcName + "'");
      return false;
    }
    return true;
  }

  public static boolean empty_element_parsed_guard_(PsiBuilder builder, String funcName, int pos) {
    if (pos == current_position_(builder)) {
      // sometimes this is a correct situation, therefore no explicit marker
      builder.error("Empty element parsed in '" + funcName + "' at offset " + builder.getCurrentOffset());
      return false;
    }
    return true;
  }

  public static boolean invalid_left_marker_guard_(PsiBuilder builder, PsiBuilder.Marker marker, String funcName) {
    //builder.error("Invalid left marker encountered in " + funcName_ +" at offset " + builder.getCurrentOffset());
    boolean goodMarker = marker != null; // && ((LighterASTNode)marker).getTokenType() != TokenType.ERROR_ELEMENT;
    if (!goodMarker) return false;
    ErrorState state = ErrorState.get(builder);

    return state.currentFrame != null;
  }

  public static TokenSet create_token_set_(IElementType... tokenTypes) {
    return TokenSet.create(tokenTypes);
  }

  public static boolean leftMarkerIs(PsiBuilder builder, IElementType type) {
    LighterASTNode marker = builder.getLatestDoneMarker();
    return marker != null && marker.getTokenType() == type;
  }

  private static boolean consumeTokens(PsiBuilder builder, boolean smart, int pin, IElementType... tokens) {
    ErrorState state = ErrorState.get(builder);
    if (state.completionState != null && state.predicateSign) {
      addCompletionVariant(builder, state.completionState, tokens);
    }
    // suppress single token completion
    CompletionState completionState = state.completionState;
    state.completionState = null;
    boolean result = true;
    boolean pinned = false;
    for (int i = 0, tokensLength = tokens.length; i < tokensLength; i++) {
      if (pin > 0 && i == pin) pinned = result;
      if (result || pinned) {
        boolean fast = smart && i == 0;
        if (!(fast ? consumeTokenFast(builder, tokens[i]) : consumeToken(builder, tokens[i]))) {
          result = false;
          if (pin < 0 || pinned) report_error_(builder, state, false);
        }
      }
    }
    state.completionState = completionState;
    return pinned || result;
  }

  public static boolean consumeTokens(PsiBuilder builder, int pin, IElementType... token) {
    return consumeTokens(builder, false, pin, token);
  }

  public static boolean consumeTokensSmart(PsiBuilder builder, int pin, IElementType... token) {
    return consumeTokens(builder, true, pin, token);
  }

  public static boolean parseTokens(PsiBuilder builder, int pin, IElementType... tokens) {
    return parseTokens(builder, false, pin, tokens);
  }

  public static boolean parseTokensSmart(PsiBuilder builder, int pin, IElementType... tokens) {
    return parseTokens(builder, true, pin, tokens);
  }

  public static boolean parseTokens(PsiBuilder builder, boolean smart, int pin, IElementType... tokens) {
    PsiBuilder.Marker marker = builder.mark();
    boolean result = consumeTokens(builder, smart, pin, tokens);
    if (!result) {
      marker.rollbackTo();
    }
    else {
      marker.drop();
    }
    return result;
  }

  public static boolean consumeTokenSmart(PsiBuilder builder, IElementType token) {
    addCompletionVariantSmart(builder, token);
    return consumeTokenFast(builder, token);
  }

  public static boolean consumeTokenSmart(PsiBuilder builder, String token) {
    addCompletionVariantSmart(builder, token);
    return consumeTokenFast(builder, token);
  }

  public static boolean consumeToken(PsiBuilder builder, IElementType token) {
    addVariantSmart(builder, token, true);
    if (nextTokenIsFast(builder, token)) {
      builder.advanceLexer();
      return true;
    }
    return false;
  }

  public static boolean consumeTokenFast(PsiBuilder builder, IElementType token) {
    if (nextTokenIsFast(builder, token)) {
      builder.advanceLexer();
      return true;
    }
    return false;
  }

  public static boolean consumeToken(PsiBuilder builder, String text) {
    return consumeToken(builder, text, ErrorState.get(builder).caseSensitive);
  }

  public static boolean consumeToken(PsiBuilder builder, String text, boolean caseSensitive) {
    addVariantSmart(builder, text, true);
    int count = nextTokenIsFast(builder, text, caseSensitive);
    if (count > 0) {
      while (count-- > 0) builder.advanceLexer();
      return true;
    }
    return false;
  }

  public static boolean consumeTokenFast(PsiBuilder builder, String text) {
    int count = nextTokenIsFast(builder, text, ErrorState.get(builder).caseSensitive);
    if (count > 0) {
      while (count-- > 0) builder.advanceLexer();
      return true;
    }
    return false;
  }

  public static boolean consumeToken(PsiBuilder builder, TokenSet tokens) {
    addVariantSmart(builder, tokens.getTypes(), true);
    return consumeTokenFast(builder, tokens);
  }

  public static boolean consumeTokenSmart(PsiBuilder builder, TokenSet tokens) {
    addCompletionVariantSmart(builder, tokens.getTypes());
    return consumeTokenFast(builder, tokens);
  }

  public static boolean consumeTokenFast(PsiBuilder builder, TokenSet tokens) {
    if (nextTokenIsFast(builder, tokens)) {
      builder.advanceLexer();
      return true;
    }
    return false;
  }

  public static boolean nextTokenIsFast(PsiBuilder builder, IElementType token) {
    return builder.getTokenType() == token;
  }

  public static boolean nextTokenIsFast(PsiBuilder builder, IElementType... tokens) {
    IElementType tokenType = builder.getTokenType();
    for (IElementType token : tokens) {
      if (token == tokenType) return true;
    }
    return false;
  }

  public static boolean nextTokenIsFast(PsiBuilder builder, TokenSet tokens) {
    return tokens.contains(builder.getTokenType());
  }

  public static boolean nextTokenIsSmart(PsiBuilder builder, IElementType token) {
    return nextTokenIsFast(builder, token) || ErrorState.get(builder).completionState != null;
  }

  public static boolean nextTokenIsSmart(PsiBuilder builder, IElementType... tokens) {
    return nextTokenIsFast(builder, tokens) || ErrorState.get(builder).completionState != null;
  }

  public static boolean nextTokenIs(PsiBuilder builder, String frameName, IElementType... tokens) {
    ErrorState state = ErrorState.get(builder);
    if (state.completionState != null) return true;
    boolean track = !state.suppressErrors && state.predicateCount < 2 && state.predicateSign;
    return !track ? nextTokenIsFast(builder, tokens) : nextTokenIsSlow(builder, frameName, tokens);
  }

  public static boolean nextTokenIsSlow(PsiBuilder builder, String frameName, IElementType... tokens) {
    ErrorState state = ErrorState.get(builder);
    IElementType tokenType = builder.getTokenType();
    if (isNotEmpty(frameName)) {
      addVariantInner(state, state.currentFrame, builder.rawTokenIndex(), frameName);
    }
    else {
      for (IElementType token : tokens) {
        addVariant(builder, state, token);
      }
    }
    if (tokenType == null) return false;
    for (IElementType token : tokens) {
      if (tokenType == token) return true;
    }
    return false;
  }

  public static boolean nextTokenIs(PsiBuilder builder, IElementType token) {
    if (!addVariantSmart(builder, token, false)) return true;
    return nextTokenIsFast(builder, token);
  }

  public static boolean nextTokenIs(PsiBuilder builder, String tokenText) {
    if (!addVariantSmart(builder, tokenText, false)) return true;
    return nextTokenIsFast(builder, tokenText, ErrorState.get(builder).caseSensitive) > 0;
  }

  public static boolean nextTokenIsFast(PsiBuilder builder, String tokenText) {
    return nextTokenIsFast(builder, tokenText, ErrorState.get(builder).caseSensitive) > 0;
  }

  public static int nextTokenIsFast(PsiBuilder builder, String tokenText, boolean caseSensitive) {
    CharSequence sequence = builder.getOriginalText();
    int offset = builder.getCurrentOffset();
    int endOffset = offset + tokenText.length();
    CharSequence subSequence = sequence.subSequence(offset, Math.min(endOffset, sequence.length()));

    if (!Comparing.equal(subSequence, tokenText, caseSensitive)) return 0;

    int count = 0;
    while (true) {
      int nextOffset = builder.rawTokenTypeStart(++count);
      if (nextOffset > endOffset) {
        return -count;
      }
      else if (nextOffset == endOffset) {
        break;
      }
    }
    return count;
  }

  private static void addCompletionVariantSmart(PsiBuilder builder, Object token) {
    ErrorState state = ErrorState.get(builder);
    CompletionState completionState = state.completionState;
    if (completionState != null && state.predicateSign) {
      addCompletionVariant(builder, completionState, token);
    }
  }

  private static boolean addVariantSmart(PsiBuilder builder, Object token, boolean force) {
    ErrorState state = ErrorState.get(builder);
    // skip FIRST check in completion mode
    if (state.completionState != null && !force) return false;
    builder.eof();
    if (!state.suppressErrors && state.predicateCount < 2) {
      addVariant(builder, state, token);
    }
    return true;
  }

  public static void addVariant(PsiBuilder builder, String text) {
    addVariant(builder, ErrorState.get(builder), text);
  }

  private static void addVariant(PsiBuilder builder, ErrorState state, Object o) {
    builder.eof(); // skip whitespaces
    addVariantInner(state, state.currentFrame, builder.rawTokenIndex(), o);

    CompletionState completionState = state.completionState;
    if (completionState != null && state.predicateSign) {
      addCompletionVariant(builder, completionState, o);
    }
  }

  private static void addVariantInner(ErrorState state, Frame frame, int pos, Object o) {
    Variant variant = state.VARIANTS.alloc().init(pos, o);
    if (state.predicateSign) {
      state.variants.add(variant);
      if (frame.lastVariantAt < pos) {
        frame.lastVariantAt = pos;
      }
    }
    else {
      state.unexpected.add(variant);
    }
  }

  private static void addCompletionVariant(@NotNull PsiBuilder builder, @NotNull CompletionState completionState, Object o) {
    int offset = builder.getCurrentOffset();
    if (!builder.eof() && offset == builder.rawTokenTypeStart(1)) return; // suppress for zero-length tokens
    String text = completionState.convertItem(o);
    int length = text == null ? 0 : text.length();
    boolean add = length != 0 && completionState.prefixMatches(builder, text);
    add = add && length > 1 && !(text.charAt(0) == '<' && text.charAt(length - 1) == '>') &&
          !(text.charAt(0) == '\'' && text.charAt(length - 1) == '\'' && length < 5);
    if (add) {
      completionState.addItem(builder, text);
    }
  }

  public static boolean isWhitespaceOrComment(@NotNull PsiBuilder builder, @Nullable IElementType type) {
    return ((PsiBuilderImpl)((Builder)builder).getDelegate()).whitespaceOrComment(type);
  }

  private static boolean wasAutoSkipped(@NotNull PsiBuilder builder, int steps) {
    for (int i = -1; i >= -steps; i--) {
      if (!isWhitespaceOrComment(builder, builder.rawLookup(i))) return false;
    }
    return true;
  }

  // here's the new section API for compact parsers & less IntelliJ platform API exposure
  public static final int _NONE_       = 0x0;
  public static final int _COLLAPSE_   = 0x1;
  public static final int _LEFT_       = 0x2;
  public static final int _LEFT_INNER_ = 0x4;
  public static final int _AND_        = 0x8;
  public static final int _NOT_        = 0x10;
  public static final int _UPPER_      = 0x20;

  // simple enter/exit methods pair that doesn't require frame object
  public static PsiBuilder.Marker enter_section_(PsiBuilder builder) {
    ErrorState state = ErrorState.get(builder);
    reportFrameError(builder, state);
    state.level++;
    return builder.mark();
  }

  public static void exit_section_(PsiBuilder builder,
                                   PsiBuilder.Marker marker,
                                   @Nullable IElementType elementType,
                                   boolean result) {
    ErrorState state = ErrorState.get(builder);
    close_marker_impl_(state.currentFrame, marker, elementType, result);
    run_hooks_impl_(builder, state, result ? elementType : null);
    state.level--;
  }

  // complex enter/exit methods pair with frame object
  public static PsiBuilder.Marker enter_section_(PsiBuilder builder, int level, int modifiers, String frameName) {
    return enter_section_(builder, level, modifiers, null, frameName);
  }

  public static PsiBuilder.Marker enter_section_(PsiBuilder builder, int level, int modifiers) {
    return enter_section_(builder, level, modifiers, null, null);
  }

  public static PsiBuilder.Marker enter_section_(PsiBuilder builder, int level, int modifiers, IElementType elementType, String frameName) {
    reportFrameError(builder, ErrorState.get(builder));
    PsiBuilder.Marker marker = builder.mark();
    enter_section_impl_(builder, level, modifiers, elementType, frameName);
    return marker;
  }

  private static void enter_section_impl_(PsiBuilder builder, int level, int modifiers, IElementType elementType, String frameName) {
    ErrorState state = ErrorState.get(builder);
    state.level++;
    Frame frame = state.FRAMES.alloc().init(builder, state, level, modifiers, elementType, frameName);
    if (((frame.modifiers & _LEFT_) | (frame.modifiers & _LEFT_INNER_)) != 0) {
      PsiBuilder.Marker left = (PsiBuilder.Marker)builder.getLatestDoneMarker();
      if (invalid_left_marker_guard_(builder, left, frameName)) {
        frame.leftMarker = left;
      }
    }
    state.currentFrame = frame;
    if ((modifiers & _AND_) != 0) {
      if (state.predicateCount == 0 && !state.predicateSign) {
        throw new AssertionError("Incorrect false predicate sign");
      }
      state.predicateCount++;
    }
    else if ((modifiers & _NOT_) != 0) {
      state.predicateSign = state.predicateCount != 0 && !state.predicateSign;
      state.predicateCount++;
    }
  }

  public static void exit_section_(PsiBuilder builder,
                                   int level,
                                   PsiBuilder.Marker marker,
                                   boolean result,
                                   boolean pinned,
                                   @Nullable Parser eatMore) {
    exit_section_(builder, level, marker, null, result, pinned, eatMore);
  }

  public static void exit_section_(PsiBuilder builder,
                                   int level,
                                   PsiBuilder.Marker marker,
                                   @Nullable IElementType elementType,
                                   boolean result,
                                   boolean pinned,
                                   @Nullable Parser eatMore) {
    ErrorState state = ErrorState.get(builder);

    Frame frame = state.currentFrame;
    state.currentFrame = frame == null ? null : frame.parentFrame;
    if (frame != null && frame.elementType != null) elementType = frame.elementType;
    if (frame == null || level != frame.level) {
      LOG.error("Unbalanced error section: got " + frame + ", expected level " + level);
      if (frame != null) state.FRAMES.recycle(frame);
      close_marker_impl_(frame, marker, elementType, result);
      return;
    }

    close_frame_impl_(state, frame, builder, marker, elementType, result, pinned);
    exit_section_impl_(state, frame, builder, elementType, result, pinned, eatMore);
    run_hooks_impl_(builder, state, pinned || result ? elementType : null);
    state.FRAMES.recycle(frame);
    state.level--;
  }

  public static <T> void register_hook_(PsiBuilder builder, Hook<T> hook, T param) {
    ErrorState state = ErrorState.get(builder);
    state.hooks = Hooks.concat(hook, param, state.level, state.hooks);
  }

  @SafeVarargs
  public static <T> void register_hook_(PsiBuilder builder, Hook<T[]> hook, T... param) {
    ErrorState state = ErrorState.get(builder);
    state.hooks = Hooks.concat(hook, param, state.level, state.hooks);
  }

  private static void run_hooks_impl_(PsiBuilder builder, ErrorState state, @Nullable IElementType elementType) {
    if (state.hooks == null) return;
    PsiBuilder.Marker marker = elementType == null ? null : (PsiBuilder.Marker)builder.getLatestDoneMarker();
    if (elementType != null && marker == null) {
      builder.mark().error("No expected done marker at offset " + builder.getCurrentOffset());
    }
    while (state.hooks != null && state.hooks.level >= state.level) {
      if (state.hooks.level == state.level) {
        marker = ((Hook<Object>)state.hooks.hook).run(builder, marker, state.hooks.param);
      }
      state.hooks = state.hooks.next;
    }
  }

  private static void exit_section_impl_(ErrorState state,
                                         Frame frame,
                                         PsiBuilder builder,
                                         @Nullable IElementType elementType,
                                         boolean result,
                                         boolean pinned,
                                         @Nullable Parser eatMore) {
    int initialPos = builder.rawTokenIndex();
    replace_variants_with_name_(state, frame, builder, elementType, result, pinned);
    int lastErrorPos = frame.lastVariantAt < 0 ? initialPos : frame.lastVariantAt;
    if (!state.suppressErrors && eatMore != null) {
      state.suppressErrors = true;
      final boolean eatMoreFlagOnce = !builder.eof() && eatMore.parse(builder, frame.level + 1);
      boolean eatMoreFlag = eatMoreFlagOnce || !result && frame.position == initialPos && lastErrorPos > frame.position;

      PsiBuilderImpl.ProductionMarker latestDoneMarker =
        (pinned || result) && (state.altMode || elementType != null) &&
        eatMoreFlagOnce ? getLatestExtensibleDoneMarker(builder) : null;
      // advance to the last error pos
      // skip tokens until lastErrorPos. parseAsTree might look better here...
      int parenCount = 0;
      while ((eatMoreFlag || parenCount > 0) && builder.rawTokenIndex() < lastErrorPos) {
        IElementType tokenType = builder.getTokenType();
        if (state.braces != null) {
          if (tokenType == state.braces[0].getLeftBraceType()) parenCount ++;
          else if (tokenType == state.braces[0].getRightBraceType()) parenCount --;
        }
        if (!(builder.rawTokenIndex() < lastErrorPos)) break;
        state.tokenAdvancer.parse(builder, frame.level + 1);
        eatMoreFlag = eatMore.parse(builder, frame.level + 1);
      }
      boolean errorReported = frame.errorReportedAt == initialPos || !result && frame.errorReportedAt >= frame.position;
      if (errorReported || eatMoreFlag) {
        if (!errorReported) {
          errorReported = reportError(builder, state, frame, false, true, true);
        }
        else if (eatMoreFlag) {
          state.tokenAdvancer.parse(builder, frame.level + 1);
        }
        if (eatMore.parse(builder, frame.level + 1)) {
          parseAsTree(state, builder, frame.level + 1, DUMMY_BLOCK, true, state.tokenAdvancer, eatMore);
        }
      }
      else if (eatMoreFlagOnce || !result && frame.position != builder.rawTokenIndex() || frame.errorReportedAt > initialPos) {
        errorReported = reportError(builder, state, frame, false, true, false);
      }
      else if (!result && pinned && frame.errorReportedAt < 0) {
        errorReported = reportError(builder, state, frame, elementType != null, false, false);
      }
      // whitespace prefix makes the very first frame offset bigger than marker start offset which is always 0
      if (latestDoneMarker != null &&
          frame.position >= latestDoneMarker.getStartIndex() &&
          frame.position <= latestDoneMarker.getEndIndex()) {
        extend_marker_impl((PsiBuilder.Marker)latestDoneMarker);
      }
      state.suppressErrors = false;
      if (errorReported || result) {
        state.clearVariants(true, 0);
        state.clearVariants(false, 0);
        frame.lastVariantAt = -1;
        for (Frame f = frame; f != null && f.variantCount > 0; f = f.parentFrame) f.variantCount = 0;
      }
    }
    else if (!result && pinned && frame.errorReportedAt < 0) {
      // do not report if there are errors beyond current position
      if (lastErrorPos == initialPos) {
        // do not force, inner recoverRoot might have skipped some tokens
        reportError(builder, state, frame, elementType != null && (frame.modifiers & _UPPER_) == 0, false, false);
      }
      else if (lastErrorPos > initialPos) {
        // set error pos here as if it is reported for future reference
        frame.errorReportedAt = lastErrorPos;
      }
    }
    // propagate errorReportedAt up the stack to avoid duplicate reporting
    if (state.currentFrame != null) {
      if (state.currentFrame.errorReportedAt < frame.errorReportedAt) {
        state.currentFrame.errorReportedAt = frame.errorReportedAt;
      }
      if (state.currentFrame.lastVariantAt < frame.lastVariantAt) {
        state.currentFrame.lastVariantAt = frame.lastVariantAt;
      }
    }
  }

  private static void close_frame_impl_(ErrorState state,
                                        Frame frame,
                                        PsiBuilder builder,
                                        PsiBuilder.Marker marker,
                                        IElementType elementType,
                                        boolean result,
                                        boolean pinned) {
    if (((frame.modifiers & _AND_) | (frame.modifiers & _NOT_)) != 0) {
      boolean resetLastPos = !state.suppressErrors && frame.lastVariantAt < 0 && frame.position < builder.rawTokenIndex();
      close_marker_impl_(frame, marker, null, false);
      state.predicateCount--;
      if ((frame.modifiers & _NOT_) != 0) state.predicateSign = !state.predicateSign;
      marker = elementType != null && marker != null && (result || pinned) ? builder.mark() : null;
      if (resetLastPos) frame.lastVariantAt = builder.rawTokenIndex();
    }
    if (elementType != null && marker != null) {
      if (result || pinned) {
        if ((frame.modifiers & _COLLAPSE_) != 0) {
          PsiBuilderImpl.ProductionMarker last = (PsiBuilderImpl.ProductionMarker)builder.getLatestDoneMarker();
          if (last != null &&
              last.getStartIndex() == frame.position &&
              state.typeExtends(last.getTokenType(), elementType) &&
              wasAutoSkipped(builder, builder.rawTokenIndex() - last.getEndIndex())) {
            elementType = last.getTokenType();
            ((PsiBuilder.Marker)last).drop();
          }
        }
        if ((frame.modifiers & _UPPER_) != 0) {
          marker.drop();
          for (Frame f = frame.parentFrame; f != null; f = f.parentFrame) {
            if (f.elementType == null) continue;
            f.elementType = elementType;
            break;
          }
        }
        else if ((frame.modifiers & _LEFT_INNER_) != 0 && frame.leftMarker != null) {
          marker.done(elementType);
          extend_marker_impl(frame.leftMarker);
        }
        else if ((frame.modifiers & _LEFT_) != 0 && frame.leftMarker != null) {
          marker.drop();
          frame.leftMarker.precede().done(elementType);
        }
        else {
          if (frame.level == 0) builder.eof(); // skip whitespaces
          marker.done(elementType);
        }
      }
      else {
        close_marker_impl_(frame, marker, null, false);
      }
    }
    else if (result || pinned) {
      if (marker != null) marker.drop();
      if ((frame.modifiers & _LEFT_INNER_) != 0 && frame.leftMarker != null) {
        extend_marker_impl(frame.leftMarker);
      }
    }
    else {
      close_marker_impl_(frame, marker, null, false);
    }
  }

  private static void extend_marker_impl(PsiBuilder.Marker marker) {
    PsiBuilder.Marker precede = marker.precede();
    IElementType elementType = ((LighterASTNode)marker).getTokenType();
    if (elementType == TokenType.ERROR_ELEMENT) {
      precede.error(notNullize(PsiBuilderImpl.getErrorMessage((LighterASTNode)marker)));
    }
    else {
      precede.done(elementType);
    }
    marker.drop();
  }

  private static void close_marker_impl_(Frame frame, PsiBuilder.Marker marker, IElementType elementType, boolean result) {
    if (marker == null) return;
    if (result) {
      if (elementType != null) {
        marker.done(elementType);
      }
      else {
        marker.drop();
      }
    }
    else {
      if (frame != null) {
        int position = ((PsiBuilderImpl.ProductionMarker)marker).getStartIndex();
        if (frame.errorReportedAt > position) {
          frame.errorReportedAt = frame.parentFrame == null ? -1 : frame.parentFrame.errorReportedAt;
        }
      }
      marker.rollbackTo();
    }
  }

  private static void replace_variants_with_name_(ErrorState state,
                                                  Frame frame,
                                                  PsiBuilder builder,
                                                  IElementType elementType,
                                                  boolean result,
                                                  boolean pinned) {
    int initialPos = builder.rawTokenIndex();
    boolean willFail = !result && !pinned;
    if (willFail && initialPos == frame.position && frame.lastVariantAt == frame.position &&
        frame.name != null && state.variants.size() >= frame.variantCount + (elementType == null ? 0 : 2)) {
      state.clearVariants(true, frame.variantCount);
      addVariantInner(state, frame, initialPos, frame.name);
    }
  }

  public static boolean report_error_(PsiBuilder builder, boolean result) {
    if (!result) report_error_(builder, ErrorState.get(builder), false);
    return result;
  }

  public static void report_error_(PsiBuilder builder, ErrorState state, boolean advance) {
    Frame frame = state.currentFrame;
    if (frame == null) {
      LOG.error("unbalanced enter/exit section call: got null");
      return;
    }
    int position = builder.rawTokenIndex();
    if (frame.errorReportedAt < position && frame.lastVariantAt > -1 && frame.lastVariantAt <= position) {
      reportError(builder, state, frame, false, true, advance);
    }
  }

  @Nullable
  private static PsiBuilderImpl.ProductionMarker getLatestExtensibleDoneMarker(@NotNull PsiBuilder builder) {
    PsiBuilderImpl.ProductionMarker marker = ContainerUtil.getLastItem(((Builder)builder).getProductions());
    return marker == null || marker.getTokenType() == null || !(marker instanceof PsiBuilder.Marker) ? null : marker;
  }

  private static boolean reportError(PsiBuilder builder,
                                     ErrorState state,
                                     Frame frame,
                                     boolean inner,
                                     boolean force,
                                     boolean advance) {
    int position = builder.rawTokenIndex();
    StringBuilder sb = new StringBuilder();
    state.appendExpected(sb, position, true);
    boolean empty = sb.length() == 0;
    if (!force && empty && !advance) return false;

    String actual = trim(builder.getTokenText());
    if (isEmpty(actual)) {
      sb.append(empty ? "unmatched input" : " expected");
    }
    else {
      if (!empty) sb.append(" expected, got ");
      sb.append("'").append(first(actual, MAX_ERROR_TOKEN_TEXT, true)).append("'");
      if (empty) sb.append(" unexpected");
    }
    String message = sb.toString();
    if (advance) {
      PsiBuilder.Marker mark = builder.mark();
      state.tokenAdvancer.parse(builder, frame.level + 1);
      mark.error(message);
    }
    else if (inner) {
      PsiBuilderImpl.ProductionMarker latestDoneMarker = getLatestExtensibleDoneMarker(builder);
      builder.error(message);
      if (latestDoneMarker != null &&
          frame.position >= latestDoneMarker.getStartIndex() &&
          frame.position <= latestDoneMarker.getEndIndex()) {
        extend_marker_impl((PsiBuilder.Marker)latestDoneMarker);
      }
    }
    else {
      builder.error(message);
    }
    builder.eof(); // skip whitespaces
    frame.errorReportedAt = builder.rawTokenIndex();
    return true;
  }

  private static void reportFrameError(PsiBuilder builder, ErrorState state) {
    if (state.currentFrame == null || state.suppressErrors) return;
    Frame frame = state.currentFrame;
    int pos = builder.rawTokenIndex();
    if (frame.errorReportedAt > pos) {
      // report error for previous unsuccessful frame
      LighterASTNode marker = builder.getLatestDoneMarker();
      int endOffset = marker != null ? ((PsiBuilderImpl.ProductionMarker)marker).getEndIndex() : pos + 1;
      while (endOffset <= pos && isWhitespaceOrComment(builder, builder.rawLookup(endOffset - pos))) endOffset ++;
      boolean inner = endOffset == pos;
      builder.eof();
      reportError(builder, state, frame, inner, true, false);
    }
  }

  public static final Key<CompletionState> COMPLETION_STATE_KEY = Key.create("COMPLETION_STATE_KEY");

  public static class CompletionState implements Function<Object, String> {
    public final int offset;
    public final Collection<String> items = new THashSet<>();

    public CompletionState(int offset_) {
      offset = offset_;
    }

    @Nullable
    public String convertItem(Object o) {
      return o instanceof Object[] ? join((Object[]) o, this, " ") : o.toString();
    }

    @Override
    public String fun(Object o) {
      return convertItem(o);
    }

    public void addItem(@NotNull PsiBuilder builder, @NotNull String text) {
      items.add(text);
    }

    public boolean prefixMatches(@NotNull PsiBuilder builder, @NotNull String text) {
      int builderOffset = builder.getCurrentOffset();
      int diff = offset - builderOffset;
      int length = text.length();
      if (diff == 0) {
        return true;
      }
      else if (diff > 0 && diff <= length) {
        CharSequence fragment = builder.getOriginalText().subSequence(builderOffset, offset);
        return prefixMatches(fragment.toString(), text);
      }
      else if (diff < 0) {
        for (int i=-1; ; i--) {
          IElementType type = builder.rawLookup(i);
          int tokenStart = builder.rawTokenTypeStart(i);
          if (isWhitespaceOrComment(builder, type)) {
            diff = offset - tokenStart;
          }
          else if (type != null && tokenStart < offset) {
            CharSequence fragment = builder.getOriginalText().subSequence(tokenStart, offset);
            if (prefixMatches(fragment.toString(), text)) {
              diff = offset - tokenStart;
            }
            break;
          }
          else break;
        }
        return diff >= 0 && diff < length;
      }
      return false;
    }

    public boolean prefixMatches(@NotNull String prefix, @NotNull String variant) {
      boolean matches = new CamelHumpMatcher(prefix, false).prefixMatches(variant.replace(' ', '_'));
      if (matches && isWhiteSpace(prefix.charAt(prefix.length() - 1))) {
        return startsWithIgnoreCase(variant, prefix);
      }
      return matches;
    }
  }

  public static class Builder extends PsiBuilderAdapter {
    public final ErrorState state;
    public final PsiParser parser;

    public Builder(PsiBuilder builder, ErrorState state_, PsiParser parser_) {
      super(builder);
      state = state_;
      parser = parser_;
    }

    public Lexer getLexer() {
      return ((PsiBuilderImpl)myDelegate).getLexer();
    }

    @Nullable
    public List<PsiBuilderImpl.ProductionMarker> getProductions() {
      return ((PsiBuilderImpl)myDelegate).getProductions();
    }
  }

  public static PsiBuilder adapt_builder_(IElementType root, PsiBuilder builder, PsiParser parser) {
    return adapt_builder_(root, builder, parser, null);
  }

  public static PsiBuilder adapt_builder_(IElementType root, PsiBuilder builder, PsiParser parser, TokenSet[] extendsSets) {
    ErrorState state = new ErrorState();
    ErrorState.initState(state, builder, root, extendsSets);
    return new Builder(builder, state, parser);
  }

  public static class ErrorState {

    public Frame currentFrame;
    public CompletionState completionState;
    MyList<Variant> variants = new MyList<>(INITIAL_VARIANTS_SIZE);
    MyList<Variant> unexpected = new MyList<>(INITIAL_VARIANTS_SIZE / 10);

    int predicateCount;
    int level;
    boolean predicateSign = true;
    boolean suppressErrors;
    Hooks<?> hooks;

    TokenSet[] extendsSets;
    public PairProcessor<IElementType, IElementType> altExtendsChecker;
    private boolean caseSensitive;
    public BracePair[] braces;
    public Parser tokenAdvancer = TOKEN_ADVANCER;
    public boolean altMode;

    final LimitedPool<Variant> VARIANTS = new LimitedPool<>(VARIANTS_POOL_SIZE, () -> new Variant());
    final LimitedPool<Frame> FRAMES = new LimitedPool<>(FRAMES_POOL_SIZE, () -> new Frame());

    public static ErrorState get(PsiBuilder builder) {
      return ((Builder)builder).state;
    }

    public static void initState(ErrorState state, PsiBuilder builder, IElementType root, TokenSet[] extendsSets) {
      state.extendsSets = extendsSets;
      PsiFile file = builder.getUserData(FileContextUtil.CONTAINING_FILE_KEY);
      state.completionState = file == null? null: file.getUserData(COMPLETION_STATE_KEY);
      Language language = file == null? root.getLanguage() : file.getLanguage();
      state.caseSensitive = language.isCaseSensitive();
      PairedBraceMatcher matcher = LanguageBraceMatching.INSTANCE.forLanguage(language);
      state.braces = matcher == null ? null : matcher.getPairs();
      if (state.braces != null && state.braces.length == 0) state.braces = null;
    }

    public void appendExpected(@NotNull StringBuilder sb, int position, boolean expected) {
      MyList<Variant> list = expected ? variants : unexpected;
      String[] strings = new String[list.size()];
      long[] hashes = new long[strings.length];
      Arrays.fill(strings, "");
      int count = 0;
      loop: for (Variant variant : list) {
        if (position == variant.position) {
          String text = String.valueOf(variant.object);
          long hash = StringHash.calc(text);
          for (int i=0; i<count; i++) {
            if (hashes[i] == hash) continue loop;
          }
          hashes[count] = hash;
          strings[count] = text;
          count++;
        }
      }
      Arrays.sort(strings);
      count = 0;
      for (String s : strings) {
        if (s.length() == 0) continue;
        if (count++ > 0) {
          if (count > MAX_VARIANTS_TO_DISPLAY) {
            sb.append(" and ...");
            break;
          }
          else {
            sb.append(", ");
          }
        }
        char c = s.charAt(0);
        String displayText = c == '<' || isJavaIdentifierStart(c) ? s : '\'' + s + '\'';
        sb.append(displayText);
      }
      if (count > 1 && count < MAX_VARIANTS_TO_DISPLAY) {
        int idx = sb.lastIndexOf(", ");
        sb.replace(idx, idx + 1, " or");
      }
    }

    public void clearVariants(Frame frame) {
      clearVariants(true, frame == null ? 0 : frame.variantCount);
      if (frame != null) frame.lastVariantAt = -1;
    }

    void clearVariants(boolean expected, int start) {
      MyList<Variant> list = expected? variants : unexpected;
      if (start < 0 || start >= list.size()) return;
      for (int i = start, len = list.size(); i < len; i ++) {
        VARIANTS.recycle(list.get(i));
      }
      list.setSize(start);
    }

    public boolean typeExtends(IElementType child, IElementType parent) {
      if (child == parent) return true;
      if (extendsSets != null) {
        for (TokenSet set : extendsSets) {
          if (set.contains(child) && set.contains(parent)) return true;
        }
      }
      return altExtendsChecker != null && altExtendsChecker.process(child, parent);
    }
  }

  public static class Frame {
    public Frame parentFrame;
    public IElementType elementType;

    public int offset;
    public int position;
    public int level;
    public int modifiers;
    public String name;
    public int variantCount;
    public int errorReportedAt;
    public int lastVariantAt;
    public PsiBuilder.Marker leftMarker;

    public Frame() {
    }

    public Frame init(PsiBuilder builder,
                      ErrorState state,
                      int level_,
                      int modifiers_,
                      IElementType elementType_,
                      String name_) {
      parentFrame = state.currentFrame;
      elementType = elementType_;

      offset = builder.getCurrentOffset();
      position = builder.rawTokenIndex();
      level = level_;
      modifiers = modifiers_;
      name = name_;
      variantCount = state.variants.size();
      errorReportedAt = -1;
      lastVariantAt = -1;

      leftMarker = null;
      return this;
    }

    @Override
    public String toString() {
      String mod = modifiers == _NONE_ ? "_NONE_, " :
        ((modifiers & _COLLAPSE_) != 0? "_CAN_COLLAPSE_, ": "") +
        ((modifiers & _LEFT_) != 0? "_LEFT_, ": "") +
        ((modifiers & _LEFT_INNER_) != 0? "_LEFT_INNER_, ": "") +
        ((modifiers & _AND_) != 0? "_AND_, ": "") +
        ((modifiers & _NOT_) != 0? "_NOT_, ": "") +
        ((modifiers & _UPPER_) != 0 ? "_UPPER_, " : "");
      return String.format("{%s:%s:%d, %d, %s%s, %s}", offset, position, level, errorReportedAt, mod, elementType, name);
    }
  }


  private static class Variant {
    int position;
    Object object;

    public Variant init(int pos, Object o) {
      position = pos;
      object = o;
      return this;
    }

    @Override
    public String toString() {
      return "<" + position + ", " + object + ">";
    }
  }

  private static class Hooks<T> {
    final Hook<T> hook;
    final T param;
    final int level;
    final Hooks<?> next;

    Hooks(Hook<T> hook, T param, int level, Hooks next) {
      this.hook = hook;
      this.param = param;
      this.level = level;
      this.next = next;
    }

    static <E> Hooks<E> concat(Hook<E> hook, E param, int level, Hooks<?> hooks) {
      return new Hooks<>(hook, param, level, hooks);
    }
  }


  private static final int MAX_CHILDREN_IN_TREE = 10;
  private static void checkSiblings(IElementType chunkType,
                                    ArrayDeque<Pair<PsiBuilder.Marker, PsiBuilder.Marker>> parens,
                                    ArrayDeque<Pair<PsiBuilder.Marker, Integer>> siblings) {
    main:
    while (!siblings.isEmpty()) {
      Pair<PsiBuilder.Marker, PsiBuilder.Marker> parenPair = parens.peek();
      int rating = siblings.getFirst().second;
      int count = 0;
      for (Pair<PsiBuilder.Marker, Integer> pair : siblings) {
        if (pair.second != rating || parenPair != null && pair.first == parenPair.second) break main;
        if (++count >= MAX_CHILDREN_IN_TREE) {
          PsiBuilder.Marker parentMarker = pair.first.precede();
          parentMarker.setCustomEdgeTokenBinders(WhitespacesBinders.GREEDY_LEFT_BINDER, null);
          while (count-- > 0) {
            siblings.removeFirst();
          }
          parentMarker.done(chunkType);
          siblings.addFirst(Pair.create(parentMarker, rating + 1));
          continue main;
        }
      }
      break;
    }
  }

  public static boolean parseAsTree(ErrorState state, PsiBuilder builder, int level,
                                    IElementType chunkType, boolean checkBraces,
                                    Parser parser, Parser eatMoreCondition) {
    ArrayDeque<Pair<PsiBuilder.Marker, PsiBuilder.Marker>> parens = new ArrayDeque<>(4);
    ArrayDeque<Pair<PsiBuilder.Marker, Integer>> siblings = new ArrayDeque<>();
    PsiBuilder.Marker marker = null;

    IElementType lBrace = checkBraces && state.braces != null && state.braces.length > 0 ? state.braces[0].getLeftBraceType() : null;
    IElementType rBrace = lBrace != null ? state.braces[0].getRightBraceType() : null;
    int totalCount = 0;
    int tokenCount = 0;
    if (lBrace != null) {
      int tokenIdx = -1;
      while (builder.rawLookup(tokenIdx) == TokenType.WHITE_SPACE) tokenIdx --;
      LighterASTNode doneMarker = builder.rawLookup(tokenIdx) == lBrace ? builder.getLatestDoneMarker() : null;
      if (doneMarker != null && doneMarker.getStartOffset() == builder.rawTokenTypeStart(tokenIdx) && doneMarker.getTokenType() == TokenType.ERROR_ELEMENT) {
        parens.add(Pair.create(((PsiBuilder.Marker)doneMarker).precede(), null));
      }
    }
    int c = current_position_(builder);
    while (true) {
      IElementType tokenType = builder.getTokenType();
      if (lBrace != null && (tokenType == lBrace || tokenType == rBrace && !parens.isEmpty())) {
        if (marker != null) {
          marker.done(chunkType);
          siblings.addFirst(Pair.create(marker, 1));
          marker = null;
          tokenCount = 0;
        }
        if (tokenType == lBrace) {
          Pair<PsiBuilder.Marker, Integer> prev = siblings.peek();
          parens.addFirst(Pair.create(builder.mark(), Pair.getFirst(prev)));
        }
        checkSiblings(chunkType, parens, siblings);
        state.tokenAdvancer.parse(builder, level);
        if (tokenType == rBrace) {
          Pair<PsiBuilder.Marker, PsiBuilder.Marker> pair = parens.removeFirst();
          pair.first.done(chunkType);
          // drop all markers inside parens
          while (!siblings.isEmpty() && siblings.getFirst().first != pair.second) {
            siblings.removeFirst();
          }
          siblings.addFirst(Pair.create(pair.first, 1));
          checkSiblings(chunkType, parens, siblings);
        }
      }
      else {
        if (marker == null) {
          marker = builder.mark();
          marker.setCustomEdgeTokenBinders(WhitespacesBinders.GREEDY_LEFT_BINDER, null);
        }
        boolean result = (!parens.isEmpty() || eatMoreCondition.parse(builder, level + 1)) &&
                         parser.parse(builder, level + 1);
        if (result) {
          tokenCount++;
          totalCount++;
        }
        else {
          break;
        }
      }

      if (tokenCount >= MAX_CHILDREN_IN_TREE) {
        marker.done(chunkType);
        siblings.addFirst(Pair.create(marker, 1));
        checkSiblings(chunkType, parens, siblings);
        marker = null;
        tokenCount = 0;
      }
      if (!empty_element_parsed_guard_(builder, "parseAsTree", c)) break;
      c = current_position_(builder);
    }
    if (marker != null) marker.drop();
    for (Pair<PsiBuilder.Marker, PsiBuilder.Marker> pair : parens) {
      pair.first.drop();
    }
    return totalCount != 0;
  }

  private static class DummyBlockElementType extends IElementType implements ICompositeElementType {
    DummyBlockElementType() {
      super("DUMMY_BLOCK", Language.ANY);
    }

    @NotNull
    @Override
    public ASTNode createCompositeNode() {
      return new DummyBlock();
    }
  }

  public static class DummyBlock extends CompositePsiElement {
    DummyBlock() {
      super(DUMMY_BLOCK);
    }

    @Override
    public PsiReference @NotNull [] getReferences() {
      return PsiReference.EMPTY_ARRAY;
    }

    @NotNull
    @Override
    public Language getLanguage() {
      return getParent().getLanguage();
    }
  }

  private static class MyList<E> extends ArrayList<E> {
    MyList(int initialCapacity) {
      super(initialCapacity);
    }

    protected void setSize(int fromIndex) {
      removeRange(fromIndex, size());
    }

    @Override
    public boolean add(E e) {
      int size = size();
      if (size >= MAX_VARIANTS_SIZE) {
        removeRange(MAX_VARIANTS_SIZE / 4, size - MAX_VARIANTS_SIZE / 4);
      }
      return super.add(e);
    }
  }
}
